It is common for two-way high frequency satellite communication systems to use separate frequency bands for transmit and receive. For example, Ka-Band satellites use frequencies near 20 GHz for user reception and use frequencies near 30 GHz for user transmissions. The required polarizations are frequently of circular sense and are orthogonal at the transmission and receive bands. Some commercial and military Ka-Band satellites use Right Handed Circular Polarization (RHCP) on the uplink and Left Handed Circular Polarization (LHCP) on the downlink. Furthermore, there are cases that require switchable orthogonal polarizations (i.e., either RHCP/LCHP or LHCP/RHCP pairs for receive and transmit). Mobile user antennas often use array antennas in order to maximize the performance within a constrained available volume. For example, on an airborne mobile platform having an antenna in the radome, the height and width of the radome is typically constrained to reduce drag forces and vulnerability to a bird strike.
Such array antennas are frequently linearly polarized and use an external polarizing component to convert linear polarization to circular polarization. If the array antenna supports two orthogonal linear polarizations, a meanderline polarizer will naturally result in orthogonally circularly polarized radio frequency (RF) signals. Specifically, a single meanderline (or equivalent) polarizer with a single linearly polarized antenna converts linear polarization to a single sense circular polarization and not to orthogonal sense circular polarizations that are needed for a Ka-Band antenna operating at 20 GHz and at 30 GHz).
For the reasons stated above and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the specification, there is a need in the art for improved systems and methods.